The present invention relates to a valved over-the-wire catheter. More particularly, the present invention relates a valved over-the-wire catheter with a hydrophilicly sealable distal tip capable of passing a guidewire.
Catheters are well known for use with the human body as part of diagnostic or treatment procedures. Such devices are typically introduced through body lumens such as blood vessels and are advanced to an area designated for diagnosis or treatment. For example, a central venous catheter is often used to provide intravenous access into a portion of a person""s blood system. The central venous catheter may then be used to inject or withdraw fluids into or from a patient""s blood stream. The injection of a medication and the withdrawal of a blood sample are common uses of a central venous catheter.
One type of catheter used for such intravenous access has an open distal, or implantable, end. The open distal end allows for the injection or withdrawal of fluids between the lumen of the catheter and the body lumen. The proximal, or non-implantable, end of the catheter is connected to a syringe or other suitable device for injecting or withdrawing fluid to or from the lumen of the catheter.
Another type of catheter for such intravenous access has a closed distal end. A closed-end catheter typically has infusion or aspiration valves at the distal end for injecting or withdrawing fluids. Infusion or aspiration valves are generally slits or slots in the distal tip of the catheter. Infusion is accomplished by imparting a positive pressure at an internal lumen of the catheter (i.e., a greater pressure than the vascular pressure) to inject a fluid from the catheter into the body lumen. Aspiration is accomplished by applying negative pressure (i.e., a pressure less than the vascular pressure) within the catheter lumen to draw vascular fluid into the catheter lumen. The infusion/aspiration valves typically open with moderate or low pressure or mechanical force and close upon the removal of that pressure or force. The proximal end is connected to a syringe or other suitable device for injecting or withdrawing fluids.
A closed-distal-end catheter is configured to minimize contact between the interior lumen of the catheter and the environment outside of the catheter, i.e., a body lumen. Such contact is minimized because the distal tip is closed and the infusion and aspiration valves can be closed to isolate the interior lumen of the catheter from its outside environment. The interior lumen of an open-distal-end catheter cannot be so isolated from its outside environment, thereby increasing the potential for thrombosis, for instance, thrombosis formation at the open distal tip.
A closed-distal-end catheter, however, cannot be easily exchanged over a guidewire. A guidewire is useful in certain procedures. For instance, if a catheter is to be advanced to a body site through a tortuous vascular path or through small vascular lumens, then the use of a guidewire may facilitate the placement of the catheter. In such a case, the guidewire may be advanced to a desired body site, and the open-distal-ended catheter may be then slidingly engaged along the guidewire to the desired body site. When the distal tip of the catheter is at the desired site, the guidewire is removed while keeping the catheter positioned at the desired site. Moreover, if an indwelling catheter has to be exchanged with a replacement catheter, then a guidewire may be used to remove the indwelling catheter and to position the replacement catheter at the same site. After the exchange, the guidewire is removed.
To use a guidewire with a closed-distal-end catheter, the guidewire, if possible, is passed through the infusion or aspiration valves at the distal end of the catheter. The passing of guidewires through these valves, however, often runs the risk of damaging the valve integrity. Such damage may prevent the valve from providing a fluid tight seal between the vascular lumen and the interior lumen of the catheter. Moreover, it is often difficult to pass a guidewire through a valve of an indwelling catheter because the valves are typically located in the wall of the catheter, thereby making passage of a guidewire difficult.
Accordingly, it is desirable to provide a catheter capable of passing over a guidewire without the disadvantages as described above. More desirably, there is a need for a valved catheter with the ability to navigate through small vascular lumens typical of some treatment areas while also having the capability of being slidably engaged and disengaged over a guidewire without the disadvantages of typical closed-ended catheters.
The present invention is directed to a catheter in the form of a sealable means for sealing the distal end of the catheter after passing a guidewire. The sealable means is a valve capable of hydrophilic expansion upon contact with an aqueous fluid. Initially, the distal end is open as the catheter is implanted into a vascular lumen. Such an open end allows for easy passage of a guidewire through the distal end. Upon contact with an aqueous fluid the valve closes to seal the distal end of the catheter with the guidewire thereat to form a distal tip with a smooth, contoured profile more typical of a closed-end catheter to reduce the potential of thrombosis.
The valve at the distal end of the catheter incorporates a lubricous composition to facilitate longitudinal movement of a guidewire therethrough. The lubricous composition is pliable so that the valve is adaptable for infusion without effecting the integrity of the valve surface for maintaining a fluid tight seal.